1
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Schmid SP, Schlosser L, Glorius F, Jorner K. Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis. Beilstein J Org Chem 2024; 20:2280-2304. [PMID: 39290209 PMCID: PMC11406055 DOI: 10.3762/bjoc.20.196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 08/09/2024] [Indexed: 09/19/2024] Open
Abstract
Organocatalysis has established itself as a third pillar of homogeneous catalysis, besides transition metal catalysis and biocatalysis, as its use for enantioselective reactions has gathered significant interest over the last decades. Concurrent to this development, machine learning (ML) has been increasingly applied in the chemical domain to efficiently uncover hidden patterns in data and accelerate scientific discovery. While the uptake of ML in organocatalysis has been comparably slow, the last two decades have showed an increased interest from the community. This review gives an overview of the work in the field of ML in organocatalysis. The review starts by giving a short primer on ML for experimental chemists, before discussing its application for predicting the selectivity of organocatalytic transformations. Subsequently, we review ML employed for privileged catalysts, before focusing on its application for catalyst and reaction design. Concluding, we give our view on current challenges and future directions for this field, drawing inspiration from the application of ML to other scientific domains.
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Affiliation(s)
- Stefan P Schmid
- Institute of Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich CH-8093, Switzerland
| | - Leon Schlosser
- Organisch-Chemisches Institut, Universität Münster, 48149 Münster, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Universität Münster, 48149 Münster, Germany
| | - Kjell Jorner
- Institute of Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich CH-8093, Switzerland
- National Centre of Competence in Research (NCCR) Catalysis, ETH Zurich, Zurich CH-8093, Switzerland
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2
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Pereira O, Ruth M, Gerbig D, Wende RC, Schreiner PR. Leveraging Limited Experimental Data with Machine Learning: Differentiating a Methyl from an Ethyl Group in the Corey-Bakshi-Shibata Reduction. J Am Chem Soc 2024; 146:14576-14586. [PMID: 38752849 DOI: 10.1021/jacs.4c01286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
We present a case study on how to improve an existing metal-free catalyst for a particularly difficult reaction, namely, the Corey-Bakshi-Shibata (CBS) reduction of butanone, which constitutes the classic and prototypical challenge of being able to differentiate a methyl from an ethyl group. As there are no known strategies on how to address this challenge, we leveraged the power of machine learning by constructing a realistic (for a typical laboratory) small, albeit high-quality, data set of about 100 reactions (run in triplicate) that we used to train a model in combination with a key-intermediate graph (of substrate and catalyst) to predict the differences in Gibbs activation energies ΔΔG‡ of the enantiomeric reaction paths. With the help of this model, we were able to select and subsequently screen a small selection of catalysts and increase the selectivity for the CBS reduction of butanone to 80% enantiomeric excess (ee), the highest possible value achieved to date for this substrate with a metal-free catalyst, thereby also exceeding the best available enzymatic systems (64% ee) and the selectivity with Corey's original catalyst (60% ee). This translates into a >50% improvement in relative ΔG‡ from 0.9 to 1.4 kcal mol-1. We underscore the transformative potential of machine learning in accelerating catalyst design because we rely on a manageable small data set and a key-intermediate graph representing a combination of catalyst and substrate graphs in lieu of a transition-state model. Our results highlight the synergy of synthetic chemistry and data-centric approaches and provide a blueprint for future catalyst optimization.
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Affiliation(s)
- Oliver Pereira
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Marcel Ruth
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Dennis Gerbig
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Raffael C Wende
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
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3
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Rummel L, Schreiner PR. Advances and Prospects in Understanding London Dispersion Interactions in Molecular Chemistry. Angew Chem Int Ed Engl 2024; 63:e202316364. [PMID: 38051426 DOI: 10.1002/anie.202316364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/07/2023]
Abstract
London dispersion (LD) interactions are the main contribution of the attractive part of the van der Waals potential. Even though LD effects are the driving force for molecular aggregation and recognition, the role of these omnipresent interactions in structure and reactivity had been largely underappreciated over decades. However, in the recent years considerable efforts have been made to thoroughly study LD interactions and their potential as a chemical design element for structures and catalysis. This was made possible through a fruitful interplay of theory and experiment. This review highlights recent results and advances in utilizing LD interactions as a structural motif to understand and utilize intra- and intermolecularly LD-stabilized systems. Additionally, we focus on the quantification of LD interactions and their fundamental role in chemical reactions.
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Affiliation(s)
- Lars Rummel
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
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4
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Zhang G, Wodrich MD, Cramer N. Catalytic enantioselective reductive Eschenmoser-Claisen rearrangements. Science 2024; 383:395-401. [PMID: 38271525 DOI: 10.1126/science.adl3369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/19/2023] [Indexed: 01/27/2024]
Abstract
An important challenge in enantioselective catalysis is developing strategies for the precise synthesis of neighboring congested all-carbon quaternary stereocenters. The well-defined transition states of [3,3]-sigmatropic rearrangements and their underlying stereospecificity render them powerful tools for the synthesis of such arrays. However, this type of pericyclic reaction remains notoriously difficult to catalyze, especially in an enantioselective fashion. Herein, we describe an enantioselective reductive Eschenmoser-Claisen rearrangement catalyzed by chiral 1,3,2-diazaphospholene-hydrides. This developed transformation enables full control of the two newly formed acyclic stereogenic centers, leading to amides with vicinal all-carbon quaternary-tertiary or quaternary-quaternary carbon atoms.
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Affiliation(s)
- Guoting Zhang
- Laboratory of Asymmetric Catalysis and Synthesis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Matthew D Wodrich
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Nicolai Cramer
- Laboratory of Asymmetric Catalysis and Synthesis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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5
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Li WC, Yang L, Wei ZL, Liao WW. Diastereo- and Enantioselective Synthesis of Functionalized Dihydropyrans via an Organocatalytic Claisen Rearrangement/Oxa-Michael Addition Tandem Sequence. Org Lett 2023; 25:6434-6439. [PMID: 37606692 DOI: 10.1021/acs.orglett.3c02461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
A straightforward diastereo- and enantioselective Claisen rearrangement/oxa-Michael addition tandem sequence with a cinchona squaramide catalyst was described, which afforded a practical and atom-economical approach to access a range of valuable dihydropyrans in good to excellent yields with excellent stereoselectivities. The organo-bifunctional catalyst played a key role in enhancing stereoselectivity in this asymmetric tandem sequence. Moreover, the asymmetric catalytic sequential processes of the hydroalkoxylation/Claisen rearrangement/cyclization sequence and Claisen rearrangement/aza-Michael addition tandem sequence have also been afforded good yields and moderate stereoselectivities.
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Affiliation(s)
- Wen-Cheng Li
- Department of Organic Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China
| | - Lei Yang
- Department of Organic Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China
| | - Zhong-Lin Wei
- Department of Organic Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China
| | - Wei-Wei Liao
- Department of Organic Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China
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6
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Khan SA, Kumar AS, Swamy KCK. DBU-Catalyzed Ring Expansion or Ene-amine Formation Involving δ-Acetoxy Allenoates and N-Sulfonyl Hydrazides. Org Lett 2023; 25:3713-3717. [PMID: 37184439 DOI: 10.1021/acs.orglett.3c01166] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
DBU-catalyzed spiro-annulation and concomitant ring expansion/domino reaction of δ-acetoxy allenoates with cycl-2-ene-N-sulfonyl hydrazides afford ring-expanded (5 → 6, 6 → 7, and 7 → 8) products. By contrast, cycl-3-ene/ane-N-sulfonyl hydrazones under similar conditions deliver pyrazole cores with the same allenoate that involves allylic elimination in which δ-acetoxy allenoate serves as 3C-synthon. The key spirocyclic intermediates, as well as dienyl-amine intermediates, are isolated and characterized. An extension to (R)-(-)-carvone-derived sulfonyl hydrazide also led to ring expansion and gave pyrazoloazepine.
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Affiliation(s)
- Shabbir Ahmed Khan
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - A Sanjeeva Kumar
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - K C Kumara Swamy
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
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7
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Hajinasiri R. Allenoates in organic synthesis. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.133053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Xu EY, Werth J, Roos CB, Bendelsmith AJ, Sigman MS, Knowles RR. Noncovalent Stabilization of Radical Intermediates in the Enantioselective Hydroamination of Alkenes with Sulfonamides. J Am Chem Soc 2022; 144:18948-18958. [PMID: 36197450 PMCID: PMC9668373 DOI: 10.1021/jacs.2c07099] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Noncovalent interactions (NCIs) are critical elements of molecular recognition in a wide variety of chemical contexts. While NCIs have been studied extensively for closed-shell molecules and ions, very little is understood about the structures and properties of NCIs involving free radical intermediates. In this report, we describe a detailed mechanistic study of the enantioselective radical hydroamination of alkenes with sulfonamides and present evidence suggesting that the basis for asymmetric induction in this process arises from attractive NCIs between a neutral sulfonamidyl radical intermediate and a chiral phosphoric acid (CPA). We describe experimental, computational, and data science-based evidence that identifies the specific radical NCIs that form the basis for the enantioselectivity. Kinetic studies support that C-N bond formation determines the enantioselectivity. Density functional theory investigations revealed the importance of both strong H-bonding between the CPA and the N-centered radical and a network of aryl-based NCIs that serve to stabilize the favored diastereomeric transition state. The contributions of these specific aryl-based NCIs to the selectivity were further confirmed through multivariate linear regression analysis by comparing the measured enantioselectivity to computed descriptors. These results highlight the power of NCIs to enable high levels of enantioselectivity in reactions involving uncharged open-shell intermediates and expand our understanding of radical-molecule interactions.
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Affiliation(s)
- Eve Y. Xu
- Department of Chemistry, Princeton University, Princeton, New Jersey, 08544, United States
| | - Jacob Werth
- Department of Chemistry, University of Utah, Salt Lake City, Utah, 84112, United States
| | - Casey B. Roos
- Department of Chemistry, Princeton University, Princeton, New Jersey, 08544, United States
| | - Andrew J. Bendelsmith
- Department of Chemistry, Princeton University, Princeton, New Jersey, 08544, United States
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah, Salt Lake City, Utah, 84112, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey, 08544, United States
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9
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Miller E, Mai BK, Read JA, Bell WC, Derrick JS, Liu P, Toste FD. A Combined DFT, Energy Decomposition, and Data Analysis Approach to Investigate the Relationship Between Noncovalent Interactions and Selectivity in a Flexible DABCOnium/Chiral Anion Catalyst System. ACS Catal 2022; 12:12369-12385. [PMID: 37215160 PMCID: PMC10195112 DOI: 10.1021/acscatal.2c03077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Developing strategies to study reactivity and selectivity in flexible catalyst systems has become an important topic of research. Herein, we report a combined experimental and computational study aimed at understanding the mechanistic role of an achiral DABCOnium cofactor in a regio- and enantiodivergent bromocyclization reaction. It was found that electron-deficient aryl substituents enable rigidified transition states via an anion-π interaction with the catalyst, which drives the selectivity of the reaction. In contrast, electron-rich aryl groups on the DABCOnium result in significantly more flexible transition states, where interactions between the catalyst and substrate are more important. An analysis of not only the lowest-energy transition state structures but also an ensemble of low-energy transition state conformers via energy decomposition analysis and machine learning was crucial to revealing the dominant noncovalent interactions responsible for observed changes in selectivity in this flexible system.
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Affiliation(s)
- Edward Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jacquelyne A Read
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - William C Bell
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jeffrey S Derrick
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - F Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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10
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Li TP, Li RS, Hu W, Xie JX, Xu M, Feng C, Ni HL, Yu WH, Hu P, Wang BQ, Cao P. Modular Synthesis of Enantioenriched α-Chiral Homoallylic Amidines Enabled by Relay Ir/Cu Catalysis. Org Lett 2022; 24:6783-6788. [PMID: 36074995 DOI: 10.1021/acs.orglett.2c02655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cascade of Ir-catalyzed enantioselective allylic amination and Cu-catalyzed alkyne-azide cycloaddition was designed for the asymmetric synthesis of homoallylic amidines. The nucleophilic addition of an in situ-generated enantioenriched tertiary allylamine to a ketenimine intermediate triggers a rapid and stereospecific zwitterionic aza-Claisen rearrangement in a 1,3-chiral transfer manner. The approach allows modular access to enantioenriched α-chiral homoallylic amidines in high yields with a high level of enantiomeric purity.
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Affiliation(s)
- Ting-Peng Li
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Ren-Sha Li
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Wei Hu
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Jia-Xin Xie
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Minghui Xu
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Chun Feng
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Hai-Liang Ni
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Wen-Hao Yu
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China.,College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Ping Hu
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Bi-Qin Wang
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
| | - Peng Cao
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610068, China
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11
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Peluso P, Chankvetadze B. Recognition in the Domain of Molecular Chirality: From Noncovalent Interactions to Separation of Enantiomers. Chem Rev 2022; 122:13235-13400. [PMID: 35917234 DOI: 10.1021/acs.chemrev.1c00846] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
It is not a coincidence that both chirality and noncovalent interactions are ubiquitous in nature and synthetic molecular systems. Noncovalent interactivity between chiral molecules underlies enantioselective recognition as a fundamental phenomenon regulating life and human activities. Thus, noncovalent interactions represent the narrative thread of a fascinating story which goes across several disciplines of medical, chemical, physical, biological, and other natural sciences. This review has been conceived with the awareness that a modern attitude toward molecular chirality and its consequences needs to be founded on multidisciplinary approaches to disclose the molecular basis of essential enantioselective phenomena in the domain of chemical, physical, and life sciences. With the primary aim of discussing this topic in an integrated way, a comprehensive pool of rational and systematic multidisciplinary information is provided, which concerns the fundamentals of chirality, a description of noncovalent interactions, and their implications in enantioselective processes occurring in different contexts. A specific focus is devoted to enantioselection in chromatography and electromigration techniques because of their unique feature as "multistep" processes. A second motivation for writing this review is to make a clear statement about the state of the art, the tools we have at our disposal, and what is still missing to fully understand the mechanisms underlying enantioselective recognition.
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Affiliation(s)
- Paola Peluso
- Istituto di Chimica Biomolecolare ICB, CNR, Sede secondaria di Sassari, Traversa La Crucca 3, Regione Baldinca, Li Punti, I-07100 Sassari, Italy
| | - Bezhan Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Avenue 3, 0179 Tbilisi, Georgia
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12
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De Oliveira Silva A, Harper JL, Fuhr KN, Lalancette RA, Cheong PHY, Brenner-Moyer SE. DyKAT by DiCat: Stereoconvergent Dienamine-Catalyzed Claisen Rearrangements. J Org Chem 2022; 87:10105-10113. [PMID: 35881006 DOI: 10.1021/acs.joc.2c01079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This Claisen rearrangement establishes the feasibility of DyKAT of γ-epimeric enals via dienamine formation to afford enantioenriched products. γ-Aryl and -alkyl enals, and exocyclic enals that introduce quaternary centers, are all amenable substrates. Products are readily converted into pyrrolidines or cyclopentenols. Notably, a reactive dienamine intermediate has been isolated from a catalytic reaction, fully characterized, and converted to product upon reexposure to reaction conditions. Product configuration arises from a directing C-H···π interaction in the transition state.
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Affiliation(s)
- Ana De Oliveira Silva
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Jordan L Harper
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Katherine N Fuhr
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Roger A Lalancette
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Paul Ha-Yeon Cheong
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Stacey E Brenner-Moyer
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
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13
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Bierschenk SM, Pan JY, Settineri NS, Warzok U, Bergman RG, Raymond KN, Toste FD. Impact of Host Flexibility on Selectivity in a Supramolecular Host-Catalyzed Enantioselective aza-Darzens Reaction. J Am Chem Soc 2022; 144:11425-11433. [PMID: 35700232 DOI: 10.1021/jacs.2c04182] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A highly enantioselective aza-Darzens reaction (up to 99% ee) catalyzed by an enantiopure supramolecular host has been discovered. To understand the role of host structure on reaction outcome, nine new gallium(III)-based enantiopure supramolecular assemblies were prepared via substitution of the external chiral amide. Despite the distal nature of the substitution in these catalysts, changes in enantioselectivity (61 to 90% ee) in the aziridine product were observed. The enantioselectivities were correlated to the flexibility of the supramolecular host scaffold as measured by the kinetics of exchange of a model cationic guest. This correlation led to the development of a best-in-class catalyst by substituting the gallium(III)-based host with one based on indium(III), which generated the most flexible and selective catalyst.
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Affiliation(s)
- Stephen M Bierschenk
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Judy Y Pan
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Nicholas S Settineri
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ulrike Warzok
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert G Bergman
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Kenneth N Raymond
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - F Dean Toste
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
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14
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Lustosa DM, Milo A. Mechanistic Inference from Statistical Models at Different Data-Size Regimes. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Danilo M. Lustosa
- Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Anat Milo
- Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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15
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Zhang Z, Zhang J, Gao Q, Zhou Y, Yang M, Cao H, Sun T, Luo G, Cao ZC. Enantioselective alkylative cross-coupling of unactivated aromatic C-O electrophiles. Nat Commun 2022; 13:2953. [PMID: 35618745 PMCID: PMC9135759 DOI: 10.1038/s41467-022-30693-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/11/2022] [Indexed: 11/23/2022] Open
Abstract
Nonpolar alkyl moieties, especially methyl group, are frequently used to modify bioactive molecules during lead optimization in medicinal chemistry. Thus transition-metal catalyzed alkylative cross-coupling reactions by using readily available and environmentally benign C–O electrophiles have been established as powerful tools to install alkyl groups, however, the C(sp3)–C(sp2) cross-coupling via asymmetric activation of aromatic C–O bond for the synthesis of alkylated chiral compounds remains elusive. Here, we unlock a C(sp3)–C(sp2) cross-coupling via enantioselective activation of aromatic C–O bond for the efficient synthesis of versatile axially chiral 2-alkyl-2’-hydroxyl-biaryl compounds. By employing a unique chiral N-heterocyclic carbene ligand, this transformation is accomplished via nickel catalysis with good enantiocontrol. Mechanistic studies indicate that bis-ligated nickel complexes might be formed as catalytically active species in the enantioselective alkylative cross-coupling. Moreover, further derivation experiments suggest this developed methodology holds great promise for complex molecule synthesis and asymmetric catalysis. Transition-metal catalyzed alkylative cross-couplings are established, powerful tools for the installation of alkyl groups. Here, the authors unlock a C(sp3)–C(sp2) cross-coupling via the asymmetric activation of the aromatic C–O bond by bis-ligated nickel complexes for the synthesis of alkylated, axially chiral biaryl compounds.
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Affiliation(s)
- Zishuo Zhang
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Jintong Zhang
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Quan Gao
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Yu Zhou
- Institute of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Mingyu Yang
- School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi, 710119, China
| | - Haiqun Cao
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Tingting Sun
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Gen Luo
- Institute of Physical Science and Information Technology, Anhui University, Hefei, 230601, China.
| | - Zhi-Chao Cao
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, College of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China.
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16
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Hu P, Wang S, Zhuo Y. Strengthened CO2 adsorption over Ce/Al-promoted MgO for fast capture. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120518] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Abstract
Carbon–carbon bond formation by [3,3]-sigmatropic rearrangement is a fundamental and powerful method that has been used to build organic molecules for a long time. Initially, Claisen and Cope rearrangements proceeded at high temperatures with limited scopes. By introducing catalytic systems, highly functionalized substrates have become accessible for forming complex structures under mild conditions, and asymmetric synthesis can be achieved by using chiral catalytic systems. This review describes recent breakthroughs in catalytic [3,3]-sigmatropic rearrangements since 2016. Detailed reaction mechanisms are discussed to enable an understanding of the reactivity and selectivity of the reactions. Finally, this review is inspires the development of new cascade reaction pathways employing catalytic [3,3]-sigmatropic rearrangement as related methodologies for the synthesis of complex functional molecules.
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18
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Tribedi S, Sunoj RB. Molecular insights into chirality transfer from double axially chiral phosphoric acid in a synergistic enantioselective intramolecular amination. Chem Sci 2022; 13:1323-1334. [PMID: 35222916 PMCID: PMC8809490 DOI: 10.1039/d1sc05749a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/26/2021] [Indexed: 11/21/2022] Open
Abstract
In the most general practice of asymmetric catalysis, a chiral catalyst, typically bearing a center or an axis of chirality, is employed as the chiral source for imparting enantiocontrol over the developing product. Given the current interest toward optically pure compounds, various forms of chiral induction enabled by diverse chiral sources as well as the use of multiple catalysts under one-pot conditions have been in focus. In one such promising development, an achiral N-sulfonamide protected 1,6-amino allyl alcohol (NaphSO2NHCH2C(Ph)2CH2CH
Created by potrace 1.16, written by Peter Selinger 2001-2019
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CHCH2OH) was subjected to Tsuji–Trost activation and an intramolecular amination to form important chiral pyrrolidine frameworks. A dual catalytic system comprising Pd(PPh3)4 and DAPCy (β-cyclohexyl substituted double axially chiral phosphoric acid derived from two homocoupled BINOL backbones with a dynamic central chiral axis) under mild conditions was reported to offer quantitative conversion with an ee of 95%. Here, we provide molecular insights into the origin of chiral induction by DAPCy, as obtained through a comprehensive density functional theory (SMD(toluene)/B3LYP-D3/6-31G**,Pd(SDD)) investigation. Two key steps in the mechanism are identified to involve a cooperative mode of activation of the Pd-bound allyl alcohol in the form of a Pd-π-allyl moiety at one end of the substrate, followed by an intramolecular nucleophilic addition of N-sulfonamide from the other end to yield a pyrrolidine derivative bearing an α-vinyl stereogenic center. (S,R,S)-DAPCy is found to steer the dehydroxylation to yield a Pd-π-allyl intermediate with a suitably poised si prochiral face for the nucleophilic addition. In the enantiocontrolled (as well as the turn-over determining step) nucleophilic addition, the chiral catalyst is identified to serve as a chiral phosphate counterion. The chiral induction is facilitated by a series of N–H⋯O, C–H⋯O, C–H⋯π, lone pair (lp)⋯π, O–H⋯O, O–H⋯π, and π⋯π noncovalent interactions, which is noted as more effective in the lower energy C–N bond formation transition state through the si prochiral face of the Pd-π-allyl moiety. These insights into the novel dynamic axially double chiral catalyst could be valuable toward exploiting such modes of stereoinduction. The origin of enantiocontrol in an intramolecular amination involving Pd(PPh3)4 and a double axially chiral phosphoric acid (DAPCy) dual catalytic system is traced to a more effective series of noncovalent interactions in the lower energy C–N bond formation transition state.![]()
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Affiliation(s)
- Soumi Tribedi
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
| | - Raghavan B Sunoj
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
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19
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Khan SA, Kumar AS, Swamy KCK. Pyridine vs DABCO vs TBAB in Annulations of δ-Acetoxy Allenoates with Thioamides Leading to Dihydrothiophene, Thiopyran, and Thiazole Scaffolds. J Org Chem 2022; 87:1285-1301. [PMID: 34979805 DOI: 10.1021/acs.joc.1c02602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The same δ-acetoxy allenoates and thioamides, under DABCO, pyridine, or tetra-n-butyl ammonium bromide (TBAB) catalysis, undergo distinctly different annulations giving chemoselective routes to dihydrothiophene, thiopyran, or thiazole motifs. Thus, using pyridine in [3 + 2] annulation, dihydrothiophenes are obtained as essentially single diastereomers. By contrast, under DABCO catalysis, allenoates deliver thiopyran motifs in good to high yields through 6-exo-dig cyclization. In the thiazole forming [3 + 2] annulation, tetra-n-butyl ammonium bromide (TBAB) facilitates addition-elimination and 5-exo-trig cyclization in which β- and γ-carbons of allenoates participate to deliver thiazole cores exclusively with a Z-isomeric exocyclic double bond. A possible rationale for these observations is delved into.
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Affiliation(s)
- Shabbir Ahmed Khan
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - A Sanjeeva Kumar
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - K C Kumara Swamy
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
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20
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Gallarati S, Laplaza R, Corminboeuf C. Harvesting the fragment-based nature of bifunctional organocatalysts to enhance their activity. Org Chem Front 2022. [DOI: 10.1039/d2qo00550f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Enhancing the activity of bifunctional organocatalysts: a fragment-based approach coupled with activity maps helps identifying better-performing catalytic motifs.
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Affiliation(s)
- Simone Gallarati
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ruben Laplaza
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- National Center for Competence in Research – Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- National Center for Competence in Research – Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- National Center for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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21
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Champagne PA. Identifying the true origins of selectivity in chiral phosphoric acid catalyzed N-acyl-azetidine desymmetrizations. Chem Sci 2021; 12:15662-15672. [PMID: 35003597 PMCID: PMC8654023 DOI: 10.1039/d1sc04969k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/10/2021] [Indexed: 01/01/2023] Open
Abstract
The first catalytic intermolecular desymmetrization of azetidines was reported by Sun and coworkers in 2015 using a BINOL-derived phosphoric acid catalyst (J. Am. Chem. Soc. 2015, 137, 5895-5898). To uncover the mechanism of the reaction and the origins of the high enantioselectivity, Density Functional Theory (DFT) calculations were performed at the B97D3/6-311+G(2d,2p)/SMD(toluene)//B97D3/6-31G(d,p)/CPCM(toluene) level of theory. Comparison of four possible activation modes confirms that this reaction proceeds through the bifunctional activation of the azetidine nitrogen and the thione tautomer of the 2-mercaptobenzothiazole nucleophile. Upon thorough conformational sampling of the enantiodetermining transition structures (TSs), a free energy difference of 2.0 kcal mol-1 is obtained, accurately reproducing the experimentally measured 88% e.e. at 80 °C. This energy difference is due to both decreased distortion and increased non-covalent interactions in the pro-(S) TS. To uncover the true origins of selectivity, the TSs optimized with the full catalyst were compared to those optimized with a model catalyst through steric maps. It is found that the arrangements displayed by the substrates are controlled by strict primary orbital interaction requirements at the transition complex, and their ability to fit into the catalyst pocket drives the selectivity. A general model of selectivity for phosphoric acid-catalyzed azetidine desymmetrizations is proposed, which is based on the preference of the nucleophile and benzoyl group to occupy empty quadrants of the chiral catalyst pocket.
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Affiliation(s)
- Pier Alexandre Champagne
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology Newark NJ USA
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22
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Karthick T, Singh KK, Singh S, Tandon P, Narayana B. Isomers of Biologically Active 2-Aminopyrimidinium Picrate through Intrinsic Reaction Coordinate Analysis and Spectroscopic Measurements. Polycycl Aromat Compd 2021. [DOI: 10.1080/10406638.2021.2003412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- T. Karthick
- Department of Physics, School of Electrical and Electronics Engineering, SASTRA Deemed University, Thanjavur, Tamil Nadu, India
| | - Keshav Kumar Singh
- Department of Physics, University of Lucknow, Lucknow, Uttar Pradesh, India
| | - Swapnil Singh
- Faculty of Chemistry, University of Wrocław, Wrocław, Poland
| | - Poonam Tandon
- Department of Physics, University of Lucknow, Lucknow, Uttar Pradesh, India
| | - B. Narayana
- Department of Studies in Chemistry, Mangalore University, Mangalagangotri, India
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23
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Zhang J, Sun T, Zhang Z, Cao H, Bai Z, Cao ZC. Nickel-Catalyzed Enantioselective Arylative Activation of Aromatic C-O Bond. J Am Chem Soc 2021; 143:18380-18387. [PMID: 34705442 DOI: 10.1021/jacs.1c09797] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The pioneering nickel-catalyzed cross-coupling of C-O electrophiles was unlocked by Wenkert in the 1970s; however, the transition-metal-catalyzed asymmetric activation of aromatic C-O bonds has never been reported. Herein the first enantioselective activation of an aromatic C-O bond is demonstrated via the catalytic arylative ring-opening cross-coupling of diarylfurans. This transformation is facilitated via nickel catalysis in the presence of chiral N-heterocyclic carbene ligands, and chiral 2-aryl-2'-hydroxy-1,1'-binaphthyl (ArOBIN) skeletons are delivered axially in high yields with high ee. Moreover, this versatile skeleton can be transformed into various synthetic useful intermediates, chiral catalysts, and ligands by using the CH- and OH-based modifiable sites. This chemistry features mild conditions and good atom economy.
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Affiliation(s)
- Jintong Zhang
- Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Tingting Sun
- Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Zishuo Zhang
- Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Haiqun Cao
- Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Zhushuang Bai
- Shandong First Medical University, Jinan, Shandong 250117, China
| | - Zhi-Chao Cao
- Anhui Agricultural University, Hefei, Anhui 230036, China
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24
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Das M, Singh KK, Khan E, Sinha RK, Singh RK, Tandon P, Gangopadhyay D. N-Acetylcysteine versus arsenic poisoning: A mechanistic study of complexation by molecular spectroscopy and density functional theory. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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Yang Z, Gui H, Shi M. Phosphine‐Catalyzed Substitution of Allenoates with Oxindoles: An Approach to 3‐Allenic or 3‐Dienoic Oxindoles. ChemistrySelect 2021. [DOI: 10.1002/slct.202102930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ze‐ren Yang
- State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular Synthesis University of Chinese Academy of Sciences Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Hou‐ze Gui
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals East China University of Science and Technology 130 Mei Long Road Shanghai 200237 China
| | - Min Shi
- State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular Synthesis University of Chinese Academy of Sciences Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals East China University of Science and Technology 130 Mei Long Road Shanghai 200237 China
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26
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Debnath S, Kumar AS, Chauhan S, Kumara Swamy KC. Divergent Reactivity of δ- and β'-Acetoxy Allenoates with 2-Sulfonamidoindoles via Phosphine Catalysis: Entry to Dihydro-α-carboline, α-Carboline, and Spiro-cyclopentene Motifs. J Org Chem 2021; 86:11583-11598. [PMID: 34343010 DOI: 10.1021/acs.joc.1c01137] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The reactivity of 2-sulfonamidoindoles with acetoxy allenoates under phosphine catalysis depends on the disposition of the acetoxy (OAc) group on the allenoate. In the temperature-controlled [3 + 3] annulations, δ-acetoxy allenoates afforded dihydrocarboline and carboline scaffolds with carbon-nitrogen nucleophilic 2-sulfonamidoindoles, in which allenoate serves as a β-, γ-, and δ-carbon donor. At room temperature (25 °C), dihydro-α-carboline motifs were obtained exclusively through Michael addition, 1,4-proton shift, isomerization, 1,2-proton transfer, phosphine elimination, and aza-Michael addition. The higher temperature (80 °C) cascade protocol using Ph3P-Cs2CO3 combination involves addition-elimination, aza-Claisen rearrangement, tosyl migration, and aromatization as key steps to give α-carbolines containing tosyl functionality at the γ-carbon. In contrast, with β'-acetoxy allenoate, 2-sulfonamidoindole acts only as a carbo-nucleophile in (p-tolyl)3P-directed [4 + 1] spiro-annulation, leading to five-membered spiro-carbocyclic motifs essentially as single diastereomers (dr >20:1) via chemoselective carbo-annulation.
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Affiliation(s)
- Shubham Debnath
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - A Sanjeeva Kumar
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - Sachin Chauhan
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - K C Kumara Swamy
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, Telangana, India
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27
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Crawford JM, Kingston C, Toste FD, Sigman MS. Data Science Meets Physical Organic Chemistry. Acc Chem Res 2021; 54:10.1021/acs.accounts.1c00285. [PMID: 34351757 PMCID: PMC9078128 DOI: 10.1021/acs.accounts.1c00285] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
ConspectusAt the heart of synthetic chemistry is the holy grail of predictable catalyst design. In particular, researchers involved in reaction development in asymmetric catalysis have pursued a variety of strategies toward this goal. This is driven by both the pragmatic need to achieve high selectivities and the inability to readily identify why a certain catalyst is effective for a given reaction. While empiricism and intuition have dominated the field of asymmetric catalysis since its inception, enantioselectivity offers a mechanistically rich platform to interrogate catalyst-structure response patterns that explain the performance of a particular catalyst or substrate.In the early stages of an asymmetric reaction development campaign, the overarching mechanism of the reaction, catalyst speciation, the turnover limiting step, and many other details are unknown or posited based on related reactions. Considering the unclear details leading to a successful reaction, initial enantioselectivity data are often used to intuitively guide the ultimate direction of optimization. However, if the conditions of the Curtin-Hammett principle are satisfied, then measured enantioselectivity can be directly connected to the ensemble of diastereomeric transition states (TSs) that lead to the enantiomeric products, and the associated free energy difference between competing TSs (ΔΔG⧧ = -RT ln[(S)/(R)], where (S) and (R) represent the concentrations of the enantiomeric products). We, and others, speculated that this important piece of information can be leveraged to guide reaction optimization in a quantitative way.Although traditional linear free energy relationships (LFERs), such as Hammett plots, have been used to illuminate important mechanistic features, we sought to develop data science derived tools to expand the power of LFERs in order to describe complex reactions frequently encountered in modern asymmetric catalysis. Specifically, we investigated whether enantioselectivity data from a reaction can be quantitatively connected to the attributes of reaction components, such as catalyst and substrate structural features, to harness data for asymmetric catalyst design.In this context, we developed a workflow to relate computationally derived features of reaction components to enantioselectivity using data science tools. The mathematical representation of molecules can incorporate many aspects of a transformation, such as molecular features from substrate, product, catalyst, and proposed transition states. Statistical models relating these features to reaction outputs can be used for various tasks, such as performance prediction of untested molecules. Perhaps most importantly, statistical models can guide the generation of mechanistic hypotheses that are embedded within complex patterns of reaction responses. Overall, merging traditional physical organic experiments with statistical modeling techniques creates a feedback loop that enables both evaluation of multiple mechanistic hypotheses and future catalyst design. In this Account, we highlight the evolution and application of this approach in the context of a collaborative program based on chiral phosphoric acid catalysts (CPAs) in asymmetric catalysis.
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Affiliation(s)
- Jennifer M Crawford
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112, United States
| | - Cian Kingston
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112, United States
| | - F Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew S Sigman
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112, United States
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28
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Ikawa T, Yamamoto Y, Heguri A, Fukumoto Y, Murakami T, Takagi A, Masuda Y, Yahata K, Aoyama H, Shigeta Y, Tokiwa H, Akai S. Could London Dispersion Force Control Regioselective (2 + 2) Cyclodimerizations of Benzynes? YES: Application to the Synthesis of Helical Biphenylenes. J Am Chem Soc 2021; 143:10853-10859. [PMID: 34197100 DOI: 10.1021/jacs.1c05434] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In recent years, London dispersion interactions, which are the attractive component of the van der Waals potential, have been found to play an important role in controlling the regio- and/or stereoselectivity of various reactions. Particularly, the dispersion interactions between substrates and catalysts (or ligands) are dominant in various selective catalyzes. In contrast, repulsive steric interactions, rather than the attractive dispersion interactions, between bulky substituents are predominant in most of the noncatalytic reactions. Herein, we demonstrate the first example of London dispersion-controlled noncatalytic (2 + 2) cyclodimerization of substituted benzynes to selectively afford proximal biphenylenes in high yields and regioselectivities, depending on the extent of dispersion interactions in the substituents. This method can be applied for the synthesis of novel helical biphenylenes, which would be fascinating for chemists as these compounds are potential skeletons for ligands, catalysts, and medicines.
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Affiliation(s)
- Takashi Ikawa
- Laboratory of Organic Chemistry, Gifu Pharmaceutical University, Daigaku-Nishi, Gifu 501-1196, Japan
| | - Yuta Yamamoto
- Department of Chemistry, Rikkyo University, Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
| | - Akito Heguri
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yutaka Fukumoto
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tomonari Murakami
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Takagi
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuto Masuda
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kenzo Yahata
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroshi Aoyama
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| | - Hiroaki Tokiwa
- Department of Chemistry, Rikkyo University, Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
| | - Shuji Akai
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
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29
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Shoja A, Reid JP. Computational Insights into Privileged Stereocontrolling Interactions Involving Chiral Phosphates and Iminium Intermediates. J Am Chem Soc 2021; 143:7209-7215. [PMID: 33914528 DOI: 10.1021/jacs.1c03829] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The precise design of a catalyst for a given reaction is extremely difficult, often requiring a significant empirical screening campaign to afford products in high yields and enantiomeric excess. Design becomes even more challenging if one requires a catalyst that performs well for a diverse range of substrates. Such "privileged" catalysts exist, but little is known why they operate so generally. We report the results of computations which show that when substrate and catalyst features are conserved between significantly different mechanistic regimes, similar modes of activation can be invoked. As a validating case study, we explored a Hantzsch ester hydrogenation of α,β-unsaturated iminiums involving BINOL-derived chiral phosphates and find they impart asymmetric induction in an analogous fashion to their acid counterpart. Specifically, DFT calculations at the IEFPCM(1,4-dioxane)-B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level predicted enantioselectivity to be close to the experimental value (82% ee calculated, 96% ee experimental) and showed that the reaction proceeds via a transition state involving two hydrogen-bonding interactions from the iminium intermediate and nucleophile to the catalyst. These interactions lower the energy of the transition structure and provide extra rigidity to the system. This new model invokes "privileged" noncovalent interactions and leads to a new explanation for the enantioselectivity outcome, ultimately providing the basis for the development of general catalyst design principles and the translation of mechanistically disparate reaction profiles for the prediction of enantioselectivity outcomes using statistical models.
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Affiliation(s)
- Ali Shoja
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Jolene P Reid
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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30
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31
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Pedrazzani R, An J, Monari M, Bandini M. New Chiral BINOL‐Based Phosphates for Enantioselective [Au(I)]‐Catalyzed Dearomatization of β‐Naphthols with Allenamides. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100166] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Riccardo Pedrazzani
- Dipartimento di Chimica “Giacomo Ciamician” Alma Mater Studiorum – Università di Bologna Via Selmi 2 40126 Bologna Italy
| | - Juzeng An
- Dipartimento di Chimica “Giacomo Ciamician” Alma Mater Studiorum – Università di Bologna Via Selmi 2 40126 Bologna Italy
| | - Magda Monari
- Dipartimento di Chimica “Giacomo Ciamician” Alma Mater Studiorum – Università di Bologna Via Selmi 2 40126 Bologna Italy
| | - Marco Bandini
- Dipartimento di Chimica “Giacomo Ciamician” Alma Mater Studiorum – Università di Bologna Via Selmi 2 40126 Bologna Italy
- Consorzio C.I.N.M.P.I.S. Via Selmi 2 40126 Bologna Italy
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Guo X, Chen X, Cheng Y, Chang X, Li X, Li P. Organocatalytic enantioselective [2 + 4]-annulation of γ-substituted allenoates with N-acyldiazenes for the synthesis of optically active 1,3,4-oxadiazines. Org Biomol Chem 2021; 19:1727-1731. [PMID: 33538742 DOI: 10.1039/d0ob02508a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enantioselective [2 + 4]-annulation of γ-substituted allenoates with N-acyldiazenes has been developed for the first time. In the presence of an l-proline-derived DMAP analogue, the annulation proceeded smoothly to afford a broad range of 1,3,4-oxadiazine derivatives in good to excellent yields with high stereoselectivities.
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Affiliation(s)
- Xing Guo
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China. and Department of Chemistry, State Key Lab of Synthetic Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Xuling Chen
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Yuyu Cheng
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Xiaoyong Chang
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Xuechen Li
- Department of Chemistry, State Key Lab of Synthetic Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Pengfei Li
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China.
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33
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Kumar AS, Chauhan S, Swamy KCK. Contrasting Carboannulation Involving δ-Acetoxy Allenoate as a Four-Carbon Synthon Using DABCO and DMAP: Access to Spiro-carbocyclic and m-Teraryl Scaffolds. Org Lett 2021; 23:1123-1129. [PMID: 33480700 DOI: 10.1021/acs.orglett.1c00076] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Spiro-annulation involving δ-acetoxy allenoate and alkyl benzoisothiazole dioxide (N-sulfonyl ketimine) triggered by DABCO/MeCO2H combination leads to an essentially single diastereomer via chemo- and regiospecific [4 + 2]-carboannulation and a new hydroxyl group is introduced. In contrast, DMAP-catalyzed benzannulation using the same reactants affords unsymmetrical m-teraryls via Mannich coupling, sequential proton transfers, and C-N bond cleavage. Here, δ-acetoxy allenoate serves as a 4C-synthon and the carboannulation is completely base dependent and mutually exclusive.
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Affiliation(s)
- A Sanjeeva Kumar
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - Sachin Chauhan
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - K C Kumara Swamy
- School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India
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34
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Dai RH, Wang Q, Chen ZX, Tian SK. Asymmetric Aza-Claisen Rearrangement between Enantioenriched α-Chiral Allylamines and Allenones. J Org Chem 2021; 86:3065-3073. [PMID: 33417470 DOI: 10.1021/acs.joc.0c02721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
An unprecedented asymmetric aza-Claisen rearrangement between enantioenriched α-chiral allylamines and allenones was found to proceed in the absence of catalysts and additives at room temperature. The rearrangement, followed by hydrolysis, provides convenient access to structurally diverse δ-chiral β-diketones in good to excellent yields with excellent retention of enantiopurity. This protocol proved powerful for the construction of an all-carbon quaternary stereocenter with high enantiopurity.
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Affiliation(s)
- Rui-Han Dai
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis (CAS), and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Qi Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis (CAS), and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhi-Xiong Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis (CAS), and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shi-Kai Tian
- Hefei National Laboratory for Physical Sciences at the Microscale, Center for Excellence in Molecular Synthesis (CAS), and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.,Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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35
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Eschmann C, Song L, Schreiner PR. London Dispersion Interactions Rather than Steric Hindrance Determine the Enantioselectivity of the Corey-Bakshi-Shibata Reduction. Angew Chem Int Ed Engl 2021; 60:4823-4832. [PMID: 33205853 PMCID: PMC7986100 DOI: 10.1002/anie.202012760] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/22/2020] [Indexed: 12/11/2022]
Abstract
The well-known Corey-Bakshi-Shibata (CBS) reduction is a powerful method for the asymmetric synthesis of alcohols from prochiral ketones, often featuring high yields and excellent selectivities. While steric repulsion has been regarded as the key director of the observed high enantioselectivity for many years, we show that London dispersion (LD) interactions are at least as important for enantiodiscrimination. We exemplify this through a combination of detailed computational and experimental studies for a series of modified CBS catalysts equipped with dispersion energy donors (DEDs) in the catalysts and the substrates. Our results demonstrate that attractive LD interactions between the catalyst and the substrate, rather than steric repulsion, determine the selectivity. As a key outcome of our study, we were able to improve the catalyst design for some challenging CBS reductions.
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Affiliation(s)
- Christian Eschmann
- Institute of Organic Chemistry, Justus Liebig University, 35392, Giessen, Germany
| | - Lijuan Song
- Institute of Organic Chemistry, Justus Liebig University, 35392, Giessen, Germany.,Current address: Shenzhen Bay Laboratory, Shenzhen, 518055, China
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, 35392, Giessen, Germany
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36
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Eschmann C, Song L, Schreiner PR. London Dispersion Interactions Rather than Steric Hindrance Determine the Enantioselectivity of the Corey–Bakshi–Shibata Reduction. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202012760] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Christian Eschmann
- Institute of Organic Chemistry Justus Liebig University 35392 Giessen Germany
| | - Lijuan Song
- Institute of Organic Chemistry Justus Liebig University 35392 Giessen Germany
- Current address: Shenzhen Bay Laboratory Shenzhen 518055 China
| | - Peter R. Schreiner
- Institute of Organic Chemistry Justus Liebig University 35392 Giessen Germany
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37
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Griffin JD, Pancoast AR, Sigman MS. Interrogation of 2,2'-Bipyrimidines as Low-Potential Two-Electron Electrolytes. J Am Chem Soc 2021; 143:992-1004. [PMID: 33411535 PMCID: PMC7980696 DOI: 10.1021/jacs.0c11267] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
As utilization of renewable energy sources continues to expand, the need for new grid energy storage technologies such as redox flow batteries (RFBs) will be vital. Ultimately, the energy density of a RFB will be dependent on the redox potentials of the respective electrolytes, their solubility, and the number of electrons stored per molecule. With prior literature reports demonstrating the propensity of nitrogen-containing heterocycles to undergo multielectron reduction at low potentials, we focused on the development of a novel electrolyte scaffold based upon a 2,2'-bipyrimidine skeleton. This scaffold is capable of storing two electrons per molecule while also exhibiting a low (∼-2.0 V vs Fc/Fc+) reduction potential. A library of 24 potential bipyrimidine anolytes were synthesized and systematically evaluated to unveil structure-function relationships through computational evaluation. Through analysis of these relationships, it was unveiled that steric interactions disrupting the planarity of the system in the reduced state could be responsible for higher levels of degradation in certain anolytes. The major decomposition pathway was ultimately determined to be protonation of the dianion by solvent, which could be reversed by electrochemical or chemical oxidation. To validate the hypothesis of strain-induced decomposition, two new electrolytes with minimal steric encumbrance were synthesized, evaluated, and found to indeed exhibit higher stability than their sterically hindered counterparts.
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Affiliation(s)
- Jeremy D. Griffin
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Joint Center for Energy Storage Research, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States
| | - Adam R. Pancoast
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Joint Center for Energy Storage Research, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
- Joint Center for Energy Storage Research, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States
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38
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Levin MD, Ovian JM, Read JA, Sigman MS, Jacobsen EN. Catalytic Enantioselective Synthesis of Difluorinated Alkyl Bromides. J Am Chem Soc 2020; 142:14831-14837. [PMID: 32799536 DOI: 10.1021/jacs.0c07043] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report an iodoarene-catalyzed enantioselective synthesis of β,β-difluoroalkyl bromide building blocks. The transformation involves an oxidative rearrangement of α-bromostyrenes, utilizing HF-pyridine as the fluoride source and m-CPBA as the stoichiometric oxidant. A catalyst decomposition pathway was identified, which, in tandem with catalyst structure-activity relationship studies, facilitated the development of an improved catalyst providing higher enantioselectivity with lower catalyst loadings. The versatility of the difluoroalkyl bromide products was demonstrated via highly enantiospecific substitution reactions with suitably reactive nucleophiles. The origins of enantioselectivity were investigated using computed interaction energies of simplified catalyst and substrate structures, providing evidence for both CH-π and π-π transition state interactions as critical features.
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Affiliation(s)
- Mark D Levin
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - John M Ovian
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Jacquelyne A Read
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States.,Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Matthew S Sigman
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Eric N Jacobsen
- Department of Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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39
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Tsai CC, Sandford C, Wu T, Chen B, Sigman MS, Toste FD. Enantioselective Intramolecular Allylic Substitution via Synergistic Palladium/Chiral Phosphoric Acid Catalysis: Insight into Stereoinduction through Statistical Modeling. Angew Chem Int Ed Engl 2020; 59:14647-14655. [PMID: 32453890 PMCID: PMC7686151 DOI: 10.1002/anie.202006237] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/25/2020] [Indexed: 11/05/2022]
Abstract
The mode of asymmetric induction in an enantioselective intramolecular allylic substitution reaction catalyzed by a combination of palladium and a chiral phosphoric acid was investigated by a combined experimental and statistical modeling approach. Experiments to probe nonlinear effects, the reactivity of deuterium-labeled substrates, and control experiments revealed that nucleophilic attack to the π-allylpalladium intermediate is the enantio-determining step, in which the chiral phosphate anion is involved in stereoinduction. Using multivariable linear regression analysis, we determined that multiple noncovalent interactions with the chiral environment of the phosphate anion are integral to enantiocontrol in the transition state. The synthetic protocol to form chiral pyrrolidines was further applied to the asymmetric construction of C-O bonds at fully substituted carbon centers in the synthesis of chiral 2,2-disubstituted benzomorpholines.
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Affiliation(s)
- Cheng-Che Tsai
- Department of Chemistry, University of California, Berkeley Berkeley, CA 94720 (USA)
| | - Christopher Sandford
- Department of Chemistry, University of Utah 315 South 1400 East, Salt Lake City, UT 84112 (USA)
| | - Tao Wu
- Department of Chemistry, University of California, Berkeley Berkeley, CA 94720 (USA)
| | - Buyun Chen
- Department of Chemistry, University of California, Berkeley Berkeley, CA 94720 (USA)
| | - Matthew S. Sigman
- Department of Chemistry, University of Utah 315 South 1400 East, Salt Lake City, UT 84112 (USA)
| | - F. Dean Toste
- Department of Chemistry, University of California, Berkeley Berkeley, CA 94720 (USA)
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40
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Tsai C, Sandford C, Wu T, Chen B, Sigman MS, Toste FD. Enantioselective Intramolecular Allylic Substitution via Synergistic Palladium/Chiral Phosphoric Acid Catalysis: Insight into Stereoinduction through Statistical Modeling. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006237] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Cheng‐Che Tsai
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
- Present address: Department of Chemistry Tunghai University Taichung City 40704 Taiwan
| | - Christopher Sandford
- Department of Chemistry University of Utah 315 South 1400 East Salt Lake City UT 84112 USA
| | - Tao Wu
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
| | - Buyun Chen
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
| | - Matthew S. Sigman
- Department of Chemistry University of Utah 315 South 1400 East Salt Lake City UT 84112 USA
| | - F. Dean Toste
- Department of Chemistry University of California, Berkeley Berkeley CA 94720 USA
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